columninfo.c

关系型数据库 Postgresql 6.5.2

/* Module:          columninfo.c
 *
 * Description:     This module contains routines related to 
 *                  reading and storing the field information from a query.
 *
 * Classes:         ColumnInfoClass (Functions prefix: "CI_")
 *
 * API functions:   none
 *
 * Comments:        See "notice.txt" for copyright and license information.
 *
 */

#include "columninfo.h"
#include "connection.h"
#include "socket.h"
#include <stdlib.h>
#include <malloc.h>
#include <string.h>

ColumnInfoClass *
CI_Constructor()
{
ColumnInfoClass *rv;

	rv = (ColumnInfoClass *) malloc(sizeof(ColumnInfoClass));

	if (rv) {
		rv->num_fields = 0;
		rv->name = NULL;
		rv->adtid = NULL;
		rv->adtsize = NULL;
		rv->display_size = NULL;
		rv->atttypmod = NULL;
	}

	return rv;
}

void
CI_Destructor(ColumnInfoClass *self)
{
	CI_free_memory(self);

	free(self);
}

/*  Read in field descriptions.
    If self is not null, then also store the information.
	If self is null, then just read, don't store.
*/
char
CI_read_fields(ColumnInfoClass *self, ConnectionClass *conn)
{
Int2 lf;
int new_num_fields;
Oid new_adtid;
Int2 new_adtsize;
Int4 new_atttypmod = -1;
char new_field_name[MAX_MESSAGE_LEN+1];
SocketClass *sock;
ConnInfo *ci;

	sock = CC_get_socket(conn);
	ci = &conn->connInfo;

	/* at first read in the number of fields that are in the query */
	new_num_fields = (Int2) SOCK_get_int(sock, sizeof(Int2));

	mylog("num_fields = %d\n", new_num_fields);

	if (self) { 	/* according to that allocate memory */
		CI_set_num_fields(self, new_num_fields);
	}

	/* now read in the descriptions */
	for(lf = 0; lf < new_num_fields; lf++) {

		SOCK_get_string(sock, new_field_name, MAX_MESSAGE_LEN);
		new_adtid = (Oid) SOCK_get_int(sock, 4);
		new_adtsize = (Int2) SOCK_get_int(sock, 2);

		/*	If 6.4 protocol, then read the atttypmod field */
		if ( ! PROTOCOL_63(ci) && ! PROTOCOL_62(ci)) {

			mylog("READING ATTTYPMOD\n");
			new_atttypmod = (Int4) SOCK_get_int(sock, 4);

			/*	Subtract the header length */
			new_atttypmod -= 4;
			if (new_atttypmod < 0)
				new_atttypmod = -1;

		}

		mylog("CI_read_fields: fieldname='%s', adtid=%d, adtsize=%d, atttypmod=%d\n", new_field_name, new_adtid, new_adtsize, new_atttypmod);

		if (self)
			CI_set_field_info(self, lf, new_field_name, new_adtid, new_adtsize, new_atttypmod);
	}

	return (SOCK_get_errcode(sock) == 0);
}



void
CI_free_memory(ColumnInfoClass *self)
{
register Int2 lf;
int num_fields = self->num_fields;

	for (lf = 0; lf < num_fields; lf++) {
		if( self->name[lf])
			free (self->name[lf]);
	}

	/*	Safe to call even if null */
	free(self->name);
	free(self->adtid);
	free(self->adtsize);
	free(self->display_size);

	free(self->atttypmod);
}

void
CI_set_num_fields(ColumnInfoClass *self, int new_num_fields)
{
	CI_free_memory(self);	/* always safe to call */

	self->num_fields = new_num_fields;

	self->name = (char **) malloc (sizeof(char *) * self->num_fields);
	self->adtid = (Oid *) malloc (sizeof(Oid) * self->num_fields);
	self->adtsize = (Int2 *) malloc (sizeof(Int2) * self->num_fields);
	self->display_size = (Int2 *) malloc(sizeof(Int2) * self->num_fields);
	self->atttypmod = (Int4 *) malloc(sizeof(Int4) * self->num_fields);
}

void
CI_set_field_info(ColumnInfoClass *self, int field_num, char *new_name, 
                                      Oid new_adtid, Int2 new_adtsize, Int4 new_atttypmod)
{
    
	// check bounds
	if((field_num < 0) || (field_num >= self->num_fields)) {
		return;
	}

	// store the info
	self->name[field_num] = strdup(new_name);  
	self->adtid[field_num] = new_adtid;
	self->adtsize[field_num] = new_adtsize;
	self->atttypmod[field_num] = new_atttypmod;

	self->display_size[field_num] = 0;
}